This invention relates generally to fluid compressors and, more particularly, to methods and apparatus for testing fluid compressors.
Plant compressed fluid systems typically include at least one compressor that supplies compressed fluid through piping to a plurality of components. Overtime, couplings used to join components, the compressor, and piping within the plant fluid system may loosen and allow compressed fluid to escape to the atmosphere. Such leaks may decrease the operating efficiency of the compressor and the plant air system, and increase the operating costs associated with the plant fluid system.
To reduce the effects of plant compressed fluid system leaks, various testing components including ultrasonic testing devices, in-line flow metering devices, and pressure profiling systems, are used to diagnose the compressed fluid system. However, known compressed fluid testing equipment does not quantify fluid leaks, determine compressor and system performance, or provide data that can be used to diagnose and adjust compressor controls under load.
Because known diagnostic equipment does not quantify compressed fluid leaks, compressor performance and controls are often ignored or inadequately addressed in a compressed fluid system analysis. Instead, often compressor tests are focused on power consumption and no actual fluid flow measurements under known load conditions are acquired. As a result, compressor controls for inlet throttling and blowoff are often set inappropriately which increases operating costs, lowers operating efficiency, and may lead to eventual failure of the compressor.
In an exemplary embodiment, a flow meter including at least one flow valve is used to performance test system compressors. The flow meter includes a pressure vessel including at least one exit port. A flow valve is coupled to each vessel exit port and each flow valve discharges fluid from the vessel at a pre-determined flow rate. The flow valve includes a unitary body including a first end, a second end, and bore extending therethrough. The bore includes an entrance portion extending from the flow valve first end, and an exit portion extending between the entrance portion and the flow valve second end. The bore exit portion is substantially cylindrical and has a substantially constant diameter therethrough. The bore entrance portion is frusto-conical and curves outwardly from the bore exit portion such that a diameter of the bore entrance portion is variable longitudinally through the bore entrance portion, and is larger than a diameter of the bore exit portion.
During testing, the flow meter is coupled to a plant fluid system to receive a full discharge of fluid exiting the compressor. The flow meter is selectively opened to discharge fluid from the flow meter pressure vessel through at least one flow valve. Each flow valve discharges fluid at a predetermined flow rate, and as subsequent flow valves are opened, a total flow rate through the flow valves is created. The desired total flow rate represents a free fluid delivery for the compressor at a specific test pressure for the compressor. By testing the compressor at various test pressures, compressor output over a span of loads is obtained and a performance curve for the compressor is generated. Additional testing with the flow meter determines system leak volume and consumption. Because performance curves are generated in a reliable and cost-effective manner, lower system operating costs are facilitated.